Rotary piston engine

ABSTRACT

A rotary compound engine employing opposed combustion cylinders extending radially on an output shaft, pistons displaceable within the cylinders and having rods connected to each other, an eccentric stationarily mounted, bearing means connecting the piston rods to the eccentric so that actuation of the pistons causes rotation of the output shaft, cooling coils around the path of the cylinders and containing fluid for absorbing heat, a turbine driven by evaporated fluid from the cooling coils for returning power to the output shaft, a radiator for condensing the fluid media from the turbine, a pressure pump for returning the fluid media to the combustion area, a fan on the output shaft for circulating air through the radiator, a cowling for directing air from the radiator past the cooling coils, an annular fuel tank mounted in the end of the cowling opposite from the fan, and a carburetor mounted in the central space of the fuel tank for communicating the fuel tank with the cylinders.

llnite Stats fit [1 1 Foster Dec. 3, 1974 ROTARY PISTON ENGINE [75] Inventor: Merrill .1. Foster, Fox River Grove,

Ill.

[73] Assignee: Marine Industries Incorporated, Barrington, Ill.

{22] Filed: Oct. 19, 1972 [21] Appl. No.: 299,142

1,602,018 10/1926 Harvey l23/8.17

Primary ExaminerC. J. Husar Attorney, Agent, or Firm-Wegner, Stellman, McCord,

Wiles & Wood [5 7] ABSTRACT A rotary compound engine employing opposed combustion cylinders extending radially on an output shaft, pistons displaceable within the cylinders and having rods connected to each other, an eccentric stationarily mounted, bearing means connecting the piston rods to the eccentric so that actuation of the pistons causes rotation of the output shaft, cooling coils around the path of the cylinders and containing fluid for absorbing heat, a turbine driven by evaporated fluid from the cooling coils for returning power to the output shaft, a radiator for condensing the fluid media from the turbine, a pressure pump for returning the fluid media to the combustion area, a fan on the output shaft for circulating air through the radiator, a

cowling for directing air from the radiator past the cooling coils, an annular fuel tank mounted in the end of the cowling opposite from the fan, and a carburetor mounted in the central space of the fuel tank for communicating the fuel tank with the cylinders.

18 Claims, 6 Drawing Figures PATENTEL 553 31974 SKEW 10F 3 PATENTEL DEC 19 4 SHEE? 30F 3 aornnv PISTON ENGHNIE BACKGROUND OF THE INVENTlON The present invention relates to rotary piston engines of the type including opposed combustion cylinders extending outwardly from a crankcase rotatable with an output shaft, together with pistons within the cylinders and connected to a stationary block, offset from the center of rotation of the cylinders, in a manner such that actuation of the pistons causes rotation of the crankcase and the output shaft.

In prior internal combustion engines of the type under consideration here, it has been customary to provide a plurality of articulated connections between the reciprocating pistons and the eccentric reaction means in the housing for rotating the crankcase responsive to reciprocation of the pistons. For example, prior U. S. Pat. No. 1,602,018 has piston rods which are fixed relative to the associated pistons, but each piston rod utilizes a separate bearing on the inner end associated with an eccentric cam, and the inner end of each piston rod is unguided during reciprocation. in U. S. Pat. No. 3,168,082, each piston is assocaited with a piston rod or connecting rod which is pivotally connected to the piston and pivotally connected to an eccentric journal for rotating an output shaft on reciprocation of the pistons. in the prior arrangements, the many articulated connections all are subject to wear, and after extended periods of use, excessive wear leads to noise and vibration which require expensive repairs.

In order to reduce articulated connections, it is desirable to utilize a piston rod which is fixed relative to the associated piston, and at the same time it is desirable to provide for appropriate guidance of the inner end of the piston rod, even though it is fixed to the piston, so that there will be no tendency to tilt the piston in the cylinder.

SUMMARY OF THE INVENTION The present invention relates to an improved rotary piston engine including a crankcase rotatable with an output shaft, combustion cylinders extending in opposite directions from the crankcase transverse to the axis of rotation, pistons within the cylinders each including a rigidly attached piston rod, a stationary reaction means, and bearing means connecting the piston rods to the reaction means to cause rotation of the crankcase by actuation of the pistons.

The combustion cylinders include inner and outer end walls, and the piston rods are mounted in bearings on the inner cylinder end walls.

The bearing means connecting the piston rods to the stationary reaction means includes a bearing track in the crankcase transverse to the axis of the cylinders and transverse to the axis of rotation. The bearing track is secured to the inner ends of the piston connecting rods and a cam wheel within the track cooperates with the stationary reaction means.

Preferably, the stationary reaction means comprises a pin eccentric to the axis of crankcase rotation and extending transversely into the bearing track through a longitudinal slot therein.

in order'to provide for internal combustion in the cylinders, intake valving is provided on the inner cylinder end wall for admitting fuel, exhaust valving is provided on the outer cylinder end wall for venting exhaust gases, and a passage in the cylinder side wall connects opposite sides of the piston at the inner end of the piston stroke. Fuel in the combustion cylinders is ignited by a spark plug in an ignition circuit revolving with the cylinder and periodically responsive to a stationary magnet adjacent the path of rotation.

Preferably, fuel is supplied from an annular fuel tank mounted concentrically about the axis of rotation, and a carburetor is mounted in the central space of the fuel tank for supplying a mixture of fuel and air to the intake valving.

In the preferred construction illustrated herein, cooling coils are provided adjacent the path of movement of the cylinders, and the cooling coils contain a refrigerant fluid for absorbing heat from the cylinders. A turbine is driven by evaporated fluid from the cooling coils and returns power to the output shaft. Fluid exhausted from the turbine is condensed in a heat exchange means and returnedto the cooling coils.

As illustrated, a fan is provided on the output shaft for circulating cooling air through the heat exchange means for condensing exhaust fluid from the turbine. Preferably, a cowling is provided for directing the air from the heat exchange means past the cooling coils and the carburetor intake.

In order to start the engine, a starting gear is connected to the output shaft by a one-way clutch for driving the shaft while permitting it to overrun the starting gear. In order to relieve the load of the turbine during starting, the turbine is connected with the output shaft by a one-way clutch.

BRIEF DESCRIPTION OF THE DRAWINGS of FIG. 1, illustrating a heat exchange means for con densing exhaust fluid from the turbine;

FIG. 5 is a wiring diagram illustrating the ignition means; and

FIG. 6 is a view illustrating the relationship of the ignition coils relative to the stationary magnet during high speed and low speed operation.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT Referring now to the drawings in more detail, and particularly FIG. 1, a rotary compound engine embodying the principles of the present invention includes a rotary piston internal combustion engine 10, a thermal reactor 12, and a fuel tank M, all arranged in an outer cowling or casing 16. The internal combustion engine 10 is operated by means of fuel supply from the tank 14 through a carburetor 18 to drive an output shaft 20. The thermal reactor 12 provides for circulation of cooling fluid to reduce the heat of the internal combustion engine, and the heat absorbed by the cooling fluid is utilized to add power to the output shaft 20.

As shown in FIGS. 1, 2 and 3, the internal combustion engine 10 includes a housing comprising a generally circular end plate 22, a U-shaped strap or frame member 23 stretching diametrically across the end plate 22 and secured thereto for providing support for the engine components, and a casing or cover 24 of cylindrical dish-shaped configuration including an end portion 26 secured to the end plate 22. Within the housing thus provided, there is a cylindrically shaped crankcase 30 extending transverse to the axis of rotation of the output shaft and secured to the output shaft to rotate with the latter. At the left of the crankcase as viewed in FIG. 1, the output shaft is supported in a bearing 31 in turn mounted in the frame member 23. At the right, as viewed in FIG. 1, the crankcase has an annular projection 33 mounted by means of bearings 34 on a cylindrical boss 35 secured to the end plate 22. An annular seal 36 is provided at the outer end of bearings 34 between the boss 35 and the annular extension 33 of the crankcase 34).

As seen best in FIGS. 2 and 3, a pair of similar combustion cylinders 38 and 39 are mounted at opposite ends of the crankcase 30 by means of threaded connections as at 40 so that the cylinders are opposed to each and aligned with the crankcase. Each cylinder is formed with an integral outer end wall, and in order to provide an inner cylinder end wall, a plate is mounted as at 42 between the cylinder and the crankcase 30. Pistons 44 and 45 are contained within the cylinders 38 and 39 respectively, and each piston is rigidly connected to a piston rod as at d6. Each rod 46 is connected at its inner end to a tubular bearing track, tube 47 which extends transversely in the crankcase 30, that is,transverse to the axis of the crankcase and transverse to the axis of rotation of the crankcase and the output shaft 20. At the outer end, each piston rod has a reduced terminus fitted in the associated piston and secured to the piston by a threaded bushing as at 49. In order to provide for support of intermediate portions of the rigid rod connection extending between the two pistons, the inner cylinder end walls 42 are each provided with a cylindrical bearing sleeve as at 50 carrying a plurality of ball bearing members for linear displacement, supporting the associated piston rod 46.

Between each piston and the outer cylinder end wall, there is an expansible firing chamber or combustion chamber 52. In order to supply fuel to the combustion chamber, intake valving is provided on the inner cylinder end wall in the form of intake ports 53 controlled by one-way valve means as at 54 illustrated here as an annular thin resilient washer captured on end wall 42 by sleeve 50 and adapted to open when subjected to suction from the interior of the cylinder and closed when subjected to pressure from the interior of the cylinder. In order to transfer fuel from the intake end of the cylinder to the combustion chamber, the inner surface of each cylinder is formed with a plurality of longitudinal slots as at 56 having a sufficient length to communicate opposite sides of the piston when the piston is positioned at the inner end of its stroke. In order to provide for discharge of exhaust gas from the combustion chamber 52, the outer end wall of each cylinder is provided with exhaust valving including a vent as at 58 and a valve closure disc 59 on a stem 60. The stem 60 is biased outwardly toward a valve closed position by means of a spring as at 62 in piston rod 46 acting between a seat in the piston rod and the inner end of the valve stem 60. The inner end of the valve stem 60 is formed with an enlarged terminus 63 reciprocable in the piston rod 46 and captured by the bushing 49, which functions to open the exhaust valve at the inner end of the piston stroke. Fuel in the combustion chamber 52 is ignited by a spark plug as at 65.

Action of the pistons 44 and 45 is utilized to provide rotary motion of the crankcase 30 and the attached output shaft 20. This is accomplished through the medium of the bearing track 47 which is rigidly connected to the piston rods 46. The bearing track reacts relative to a stationary reaction member in the housing in the form of an eccentric pin mounted in the boss 35 parallel to the axis of rotation of the shaft 20. The pin 70 projects transversely into the open side of cam track 47 through a longitudinal slot 72. At the free end, the pin 70 carries a bushing 73 supporting a bearing member 74 having an outer surface adapted to fit the interior of the tube 47 and forming a cam means cooperating therewith.

The engine operates in a two stroke cycle as follows. Just past the deadcenter position illustrated in FIG. 2, the spark plug 65 ignites the fuel mixture in the cylinder 39, forcing the piston 45 inwardly. Assuming the direction of rotation is clockwise, the piston rod 46 is then off center beneath the bearing 74, so that the cam reaction of the sleeve 47 on the bearing 74 tends to rotate the crankcase and cylinders in a clockwise direction. Inward movement of the piston 45 also compresses the fuel in the inner end of the cylinder 39. At the inner end of the piston stroke, the recess 56 in the inner cylinder wall places the inner end of the cylinder in communication with the outer end of the cylinder. At this time, the exhaust valve has opened, and expansion of the compressed fuel from the inner end of the cylinder to the outer end of the cylinder forces the exhaust gas out of the exhaust valve. As the piston now moves outwardly in the cylinder, the exhaust valve is closed and the fuel mixture is compressed in the combustion chamber preparatory to a succeeding ignition.

Fuel is supplied to the interior of the crankcase 30 through a passage (FIG. 3) in the boss 35 secured to the end wall 22. The passage 80 in turn communicates with the carburetor 18 mounted on the outside of the end wall 22. The carburetor 18 is disposed within a central space 82 in the center of the annular fuel tank 14. The carburetor communicates with the interior of the tank through an appropriate fitting as at 83. The tank 14 is preferably supported in the end of the outer casing 16 as by means of an annular ported support member 85, so that air may circulate between the tank 14 and casing 16, and between the tank 14 and the end plate 22 to the vicinity of the carburetor 18. Also, the carburetor is spaced from the inner surface of the tank at 82 so that air may flow freely past the carburetor as indicated by arrows 86 to maintain the carburetor intake cool.

Exhaust gas discharged from the exhaust valves at the outer cylinder end walls is exhausted from the engine casing 24 through an exhaust fitting as at 88 (FIG. 1).

Each of the ignition spark plugs 65 is wired in circuit with a secondary coil 87 (FIG. 5) associated with a primary coil 88. The coils are wound on the central por tion of a U-shaped core 89 mounted on the crankcase 30. As the crankcase rotates, the free ends of the legs of the U-shaped core 89 pass a stationary magnet 90. The movement of the primary coil past the magnet induces a voltage in the primary coil which is transformed into a higher voltage in the secondary coil. The

voltage in the primary coil 88 charges a capacitor 91. In order to discharge the capacitor when the voltage in the secondary is high enough to produce an adequate spark at the plug 65, a reed switch 92 is provided in circuit with the primary coil 88 between the coil and a ground 93. The reed switch is controlled by a coil 94. Discharge of the capacitor through coil 94 is prevented by a diode 95.

In operation, with the engine running, the windings 87 and 88 on the core 89, as well as reed switch 92 and its coil 94, rotate past the stationary magnet 90 in the direction (to the right) indicated by the arrows in FIGS. 5 and 6. The reed switch contacts are normally open, but when sufficient voltage is induced in the primary coil 88, energization of coil 94 causes the reed switch contacts 92 to close at a time when the voltage in the secondary has attained a value sufficient to create an adequate ignition spark at the plug 65. Closure of the reed switch 92 discharges the capacitor 91 through the primary coil 98 to ground 93. Discharge of the capacitor through the reed switch 92 causes the high voltage in the secondary to discharge through the electrodes of the spark plug 65, creating a spark for ignition to fuel in the combustion chamber 52.

The voltage induced in coils 97 and 88 is a function of the speed of the coils past the magnet. The highest voltage occurs when the core 39 is positioned directly opposite the magnet 91) as shown in FIGS. 5 and 6. When the speed of the engine increases, the sparking voltage is attained more quickly, thus advancing the spark automatically.

In order to tire the spark plug during hand cranking, when the movement of the coils 87,88 past the magnet 99 may not be adequate to induce sufficient voltage to operate the reed switch, a second switch 98 is provided in parallel with reed switch 92, for operation either magnetically or mechanically when the coils reach the position shown in broken line in H6. 6. When the engine is running, firing at the broken line position would be too late, and discharge will occur on energization of reed switch coil 94.

As seen in F168. 1 and 2, the components of the ignitioncircuit are carried in a container 99 appropriately secured on the crankcase 39.

in order to provide for cooling of the internal combustion engine, cooling coils are located adjacent the path of travel of the cylinders 38 and 39. As seen best in FIGS. 1 and 2, the cooling coils include an inlet header 110 having a U-shaped cross section including parallel legs 111 and 112 together with a connecting cross portion 113. Diametrically opposed to the inlet header 119, there is an outlet header 115 having a configuration similar to the inlet header and including a central portion 116, and side portions 117 and 118. The inlet header 1111 and the outlet header 115 are connected by tubes for conducting refrigerant fluid from the inlet header to the outlet header. As seen best in FIG. 2, there are two groups of tubes connecting the headers, including one group 120 extending circumferentially in one direction from the inlet header 110 to the outlet header 115, and a second group 122 extending circumferentially in the opposite direction from the inlet header 119 to the outlet header 115. Each group of tubes includes a central series 123 connecting header portions 1 13 and 1 14, a side series 124 connecting header portions 111 and 117, and a side series 125 connecting header portions 112 and 118. An inlet conduit is provided for supplying fluid to the inlet header 110, and an outlet conduit 131 provides for discharge of vapor from the outlet header 115.

In order to utilize the heat energy in the cooling coils, the coils are included in a continuous cycle engine utilizing a refrigerant, such as carbon dioxide or freon, for example, which functions as a thermal reactor for add ing power to the output shaft 20. The vapor conduit 131 communicates with a nozzle 132 adjacent a turbine wheel 134 rotatably mounted in a turbine housing 135. In order to support the turbine housing, a frame plate 136 is supported on the frame member 23 by appropriate means such as bolts used with spacers 137. In turn, the turbine housing 135 is supported on the frame plate 136 by appropriate means as at 138.

Fluid exhausted from the turbine is condensed and collected in a sump 140. To this end, the turbine chamber 135 communicates with a heat exchanger or radiator including a plurality of short tubes at 142 connecting the lower portion of the turbine chamber 135 and the sump 140, and a series of longer tubes 144 connecting the upper portion of the turbine chamber 135 and the sump 140. Air is circulated between the heat exchanger tubes 142 and 144 by a fan 145 mounted on the output shaft 20. After passing through the heat exchanger tubes 142 and 144, the air is circulated around the outside of the internal combustion engine casing 26, and then outwardly of the outer casing 16 past the fuel tank 14 and the carburetor 18.

In order to transmit power from the turbine wheel 134 to the output shaft 20, the turbine is mounted on a shaft 147 carrying a gear 148 in turn meshing with a gear 149 connected by a one-way clutch 150 to the output shaft 20. The one-way clutch is arranged to allow the turbine to drive the output shaft but to relieve the load of the turbine during starting.

In order to start the engine in operation, a starter gear 152 is mounted concentrically with the output shaft 20. As illustrated, the gear 152 is in the form of a pulley for a manually accessible starter rope 153. The starter gear 152 is connected to the output shaft 20 by a one-way clutch 155 for driving the shaft in one direction while allowing the shaft to overrun the starter gear after operation is established.

Condensed fluid from the sump 140 is collected by a pump having an outlet connected to supply fluid to the inlet 130 for the inlet header 110. The pump 160 is driven by a gear 162 meshing with the turbine driven gear 149, so that the pump is driven whenever the turbine is operating.

In operation, the combined internal combustion engine and thermal reactor provide improved efficiency over that provided by either engine separately. For example, the internal combustion engine operates at about 40 percent efficiency, losing some 60 percent through heat convection, and the thermal reactor recovers approximately one third of the heat loss and provides an overall efficiency on the order of 60 percent. The fluid utilized in the thermal reactor has a vapor pressure associated with each temperature value. Thus, in a closed system, vapor will migrate toward the cooler side of the turbine, effecting work as it passes through the turbine and then condenses. The relatively small volume of condensate can reasonably be pumped back against the pressure head in view of the advantage gained in the change of state from liquid to vapor. The

ideal refrigerant media is one which will condense at atmospheric temperature and yet maintain a high pressure to temperature differential, so that the cooling coils are kept as cool as possible and thus absorb as much heat as possible, with minimum losses to atmosphere.

lt should be noted that the internal combustion engine may be operated without the thermal reactor and without a cover or housing, relying on air cooling. The cylinder would then exhaust directly to atmosphere. If desired, a nonpolluting fuel may be utilized. The internal combustion engine is essentially rotary, with the cylinders and pistons revolving about the central bearings, the cylinders in a circular orbit, and the pistons in an elliptical orbit, as the volume of the combustion chambers change. The bearings on the piston rods take the torque thrust of the pistons and the pistons thus are substantially frictionless in the cylinders. If desired, additional cylinders may be utilized, preferably in pairs axially and angularly displaced relative to other pairs.

1 claim:

1. A rotary piston engine, comprising:

a. a frame,

b. a crankcase rotatable on the frame,

c. a pair of combustion cylinders extending in opposite directions from the crankcase transverse to the axis of rotation,

d. a piston displaceable in each cylinder including a piston rod rigidly secured to the associated piston and to the other rod,

e. an eccentric pin on the frame parallel to the axis of rotation, and

f. bearing means slidably connecting the pin to the piston rods so that action of the pistons causes rotation of the crankcase.

2. A rotary piston engine, comprising:

a. a supporting frame,

b. a crankcase,

c. a pair of combustion cylinders extending in opposite directions from the crankcase and each including inner and outer end walls,

d. means mounting the crankcase and cylinders for rotation on the frame about an axis transverse to the longitudinal axis of the cylinders,

e. a piston displaceable in each cylinder including a piston rod extending through the inner cylinder end wall,

f. an elongated bearing in the crankcase transverse to the cylinder axis and transverse to the axis of rotation and secured to inner ends of the piston rods,

g. a pin on the frame eccentric to the axis of crankcase rotation and extending transversely into the bearing tube through a slot therein, and

h. bearing means on the pin slidable in the tube, so that action of the pistons causes rotation of the crankcase.

3. A rotary piston engine as defined in claim 2, wherein each piston rod is fixed to its piston and fixed to the bearing.

4. A rotary piston engine as defined in claim 2, including an output shaft rotatable with the crankcase.

5. A rotary piston engine as defined in claim 2, in-

cluding intake and exhaust valving operable in timed relation with'motion of the pistons for admitting fuel to the combustion cylinders and venting exhaust gases therefrom.

6. A rotary piston engine as defined in claim 5, including ignition means operable in timed relation with motion of the piston for igniting fuel in the cylinders.

7. A rotary piston engine, comprising:

a. a supporting frame,

b. a cylindrical crankcase rotatable on the frame about an axis transverse to the longitudinal axis of the crankcase,

c. a pair of combustion cylinders secured to opposite ends of the crankcase,

d. inner and outer end walls closing opposite ends of each cylinder,

e. a piston displaceable in each cylinder,

f. a piston rod rigidly secured to each piston and extending inwardly through the inner cylinder end wall,

g. an elongated bearing track extending transversely in the crankcase transverse to the axis of crankcase rotation and secured to the inner ends of the piston rods, h. a stationary pin mounted on the frame eccentric to the axis of crankcase rotation and extending transversely into the bearing through a longitudinal slot therein,

i. a bearing wheel rotatable on the pin and displaceable in the bearing so that actuation of the pistons causes rotation of the crankcase,

j. intake and exhaust valving associated with the cylinders to admit fuel and vent exhaust gases,

k. ignition means for lighting fuel in the combustion cylinders, and

1. an output shaft rotatable with the crankcase.

8. A rotary piston engine as defined in claim 7, wherein said valving includes an intake valve in the inner cylinder end wall, an exhaust valve in the outer cylinder side wall, and a passage in the cylinder side wall connecting opposite sides of the piston at the inner end of the piston stroke.

9. A rotary piston engine as defined in claim 7, wherein said ignition means comprises a stationary magnet on the frame adjacent the path of rotation of the cylinders and an ignition circuit for each cylinder responsive to the magnet for creating an ignition spark in timed relation with rotation.

10. A rotary piston engine as defined in claim 7, including bearing means in each inner cylinder end wall movably supporting the associated piston rod.

11. A rotary piston engine, comprising:

a. a frame,

b. a crankcase rotatable on the frame,

c. combustion cylinders extending outwardly from the crankcase transverse tothe axis of rotation,

d. a piston displaceable in each cylinder,

e. a piston rod connected to each piston,

f. cam means on the frame,

g. means connecting the cam means to the piston rods so that action of the pistons causes rotation of the crankcase,

h. cooling coils adjacent the path of movement of the cylinders containing fluid for absorbing heat from the cylinders, and

i. a circulation system for receiving evaporated fluid from the cooling coils and returning condensed fluid thereto.

12. A rotary piston engine as defined in claim 11,

wherein the cooling coils comprise an inlet header for receiving condensed fluid from the circulation system,

an outlet header diametrically opposite the inlet header for transferring evaporated fluid to the circulation system, and tubes extending from the inlet header to the outlet header along the path of the cylinders.

13. A rotary piston engine as defined in claim 12, wherein the headers and tubes are arranged in a pattern including a U-shaped cross section embracing the outer ends of the cylinders.

14. A rotary piston engine as defined in claim 11, wherein the circulation system includes a radiator for receiving evaporated fluid to cool the fluid, and a pump for supplying condensed fluid from the radiator to the cooling coils.

15. A rotary piston engine, comprising:

a. a supporting frame,

b. a crankcase rotatable on the frame and including an output shaft,

0. a pair of combustion cylinders extending in opposite directions from the crankcase transverse to the axis of rotation,

d. a piston displaceable in each cylinder,

e. a piston rod secured to each piston,

f. an eccentric on the frame parallel to the axis of crankcase rotation,

g. means connecting the piston rods to the eccentric so that action of the pistons causes rotation of the crankcase and output shaft,

h. intake and exhaust valving for admitting fuel and venting exhaust gases relative to the cylinders,

i. ignition means for lighting fuel in the cylinders,

j. cooling coils adjacent the path of the cylinders containing refrigerant fluid for absorbing heat from the cylinders, and

k. a thermal reactor for receiving evaporated fluid from the cooling coils and returning condensed 10 fluid thereto.

16. A rotary piston engine as defined in claim 15, wherein the cooling coils include an inlet chamber for receiving condensed fluid, an outlet chamber opposite the inlet chamber for collecting evaporated fluid, and tubes extending circumferentially in opposite directions from the inlet chamber to the outlet'chamber along the path of the cylinders.

17. A rotary piston engine, comprising:

a. a frame,

b. a crankcase rotatable on the frame,

c. a pair of combustion cylinders extending in opposite directions from the crankcase transverse to the axis of rotation,

d. a piston displaceable in each cylinder including a piston rod connected to each piston,

e. means on the frame connected to the piston rods so that action of the pistons causes rotation of the crankcase,

f. a fuel tank mounted at one end of the frame,

g. means for supplying fuel from the tank to the crankcase,

h. intake valving for admitting fuel from the crankcase to the cylinders,

i. exhaust valving for venting exhaust gas from the cylinders, and

j. ignition means for lighting fuel in the cylinders.

18. The rotary piston engine of claim 17, including a drive shaft rotatable with the crankcase and projecting from the end of the engine opposite the fuel tank, said fuel tank having an annular configuration, and a carburetor located in the central space of the fuel tank for supplying fuel from the tank to the crankcase. 

1. A rotary piston engine, comprising: a. a frame, b. a crankcase rotatable on the frame, c. a pair of combustion cylinders extending in opposite directions from the crankcase transverse to the axis of rotation, d. a piston displaceable in each cylinder including a piston rod rigidly secured to the associated piston and to the other rod, e. an eccentric pin on the frame parallel to the axis of rotation, and f. bearing means slidably connecting the pin to the piston rods so that action of the pistons causes rotation of the crankcase.
 2. A rotary piston engine, comprising: a. a supporting frame, b. a crankcase, c. a pair of combustion cylinders extending in opposite directions from the crankcase and each including inner and outer end walls, d. means mounting the crankcase and cylinders for rotation on the frame about an axis transverse to the longitudinal axis of the cylinders, e. a piston displaceable in each cylinder inCluding a piston rod extending through the inner cylinder end wall, f. an elongated bearing in the crankcase transverse to the cylinder axis and transverse to the axis of rotation and secured to inner ends of the piston rods, g. a pin on the frame eccentric to the axis of crankcase rotation and extending transversely into the bearing tube through a slot therein, and h. bearing means on the pin slidable in the tube, so that action of the pistons causes rotation of the crankcase.
 3. A rotary piston engine as defined in claim 2, wherein each piston rod is fixed to its piston and fixed to the bearing.
 4. A rotary piston engine as defined in claim 2, including an output shaft rotatable with the crankcase.
 5. A rotary piston engine as defined in claim 2, including intake and exhaust valving operable in timed relation with motion of the pistons for admitting fuel to the combustion cylinders and venting exhaust gases therefrom.
 6. A rotary piston engine as defined in claim 5, including ignition means operable in timed relation with motion of the piston for igniting fuel in the cylinders.
 7. A rotary piston engine, comprising: a. a supporting frame, b. a cylindrical crankcase rotatable on the frame about an axis transverse to the longitudinal axis of the crankcase, c. a pair of combustion cylinders secured to opposite ends of the crankcase, d. inner and outer end walls closing opposite ends of each cylinder, e. a piston displaceable in each cylinder, f. a piston rod rigidly secured to each piston and extending inwardly through the inner cylinder end wall, g. an elongated bearing track extending transversely in the crankcase transverse to the axis of crankcase rotation and secured to the inner ends of the piston rods, ''h. a stationary pin mounted on the frame eccentric to the axis of crankcase rotation and extending transversely into the bearing through a longitudinal slot therein, i. a bearing wheel rotatable on the pin and displaceable in the bearing so that actuation of the pistons causes rotation of the crankcase, j. intake and exhaust valving associated with the cylinders to admit fuel and vent exhaust gases, k. ignition means for lighting fuel in the combustion cylinders, and l. an output shaft rotatable with the crankcase.
 8. A rotary piston engine as defined in claim 7, wherein said valving includes an intake valve in the inner cylinder end wall, an exhaust valve in the outer cylinder side wall, and a passage in the cylinder side wall connecting opposite sides of the piston at the inner end of the piston stroke.
 9. A rotary piston engine as defined in claim 7, wherein said ignition means comprises a stationary magnet on the frame adjacent the path of rotation of the cylinders and an ignition circuit for each cylinder responsive to the magnet for creating an ignition spark in timed relation with rotation.
 10. A rotary piston engine as defined in claim 7, including bearing means in each inner cylinder end wall movably supporting the associated piston rod.
 11. A rotary piston engine, comprising: a. a frame, b. a crankcase rotatable on the frame, c. combustion cylinders extending outwardly from the crankcase transverse to the axis of rotation, d. a piston displaceable in each cylinder, e. a piston rod connected to each piston, f. cam means on the frame, g. means connecting the cam means to the piston rods so that action of the pistons causes rotation of the crankcase, h. cooling coils adjacent the path of movement of the cylinders containing fluid for absorbing heat from the cylinders, and i. a circulation system for receiving evaporated fluid from the cooling coils and returning condensed fluid thereto.
 12. A rotary piston engine as defined in claim 11, wherein the cooling coils comprise an inlet header for receiving condensed fluid from the circulation system, an outlet header diametrically opposite the inlet header for Transferring evaporated fluid to the circulation system, and tubes extending from the inlet header to the outlet header along the path of the cylinders.
 13. A rotary piston engine as defined in claim 12, wherein the headers and tubes are arranged in a pattern including a U-shaped cross section embracing the outer ends of the cylinders.
 14. A rotary piston engine as defined in claim 11, wherein the circulation system includes a radiator for receiving evaporated fluid to cool the fluid, and a pump for supplying condensed fluid from the radiator to the cooling coils.
 15. A rotary piston engine, comprising: a. a supporting frame, b. a crankcase rotatable on the frame and including an output shaft, c. a pair of combustion cylinders extending in opposite directions from the crankcase transverse to the axis of rotation, d. a piston displaceable in each cylinder, e. a piston rod secured to each piston, f. an eccentric on the frame parallel to the axis of crankcase rotation, g. means connecting the piston rods to the eccentric so that action of the pistons causes rotation of the crankcase and output shaft, h. intake and exhaust valving for admitting fuel and venting exhaust gases relative to the cylinders, i. ignition means for lighting fuel in the cylinders, j. cooling coils adjacent the path of the cylinders containing refrigerant fluid for absorbing heat from the cylinders, and k. a thermal reactor for receiving evaporated fluid from the cooling coils and returning condensed fluid thereto.
 16. A rotary piston engine as defined in claim 15, wherein the cooling coils include an inlet chamber for receiving condensed fluid, an outlet chamber opposite the inlet chamber for collecting evaporated fluid, and tubes extending circumferentially in opposite directions from the inlet chamber to the outlet chamber along the path of the cylinders.
 17. A rotary piston engine, comprising: a. a frame, b. a crankcase rotatable on the frame, c. a pair of combustion cylinders extending in opposite directions from the crankcase transverse to the axis of rotation, d. a piston displaceable in each cylinder including a piston rod connected to each piston, e. means on the frame connected to the piston rods so that action of the pistons causes rotation of the crankcase, f. a fuel tank mounted at one end of the frame, g. means for supplying fuel from the tank to the crankcase, h. intake valving for admitting fuel from the crankcase to the cylinders, i. exhaust valving for venting exhaust gas from the cylinders, and j. ignition means for lighting fuel in the cylinders.
 18. The rotary piston engine of claim 17, including a drive shaft rotatable with the crankcase and projecting from the end of the engine opposite the fuel tank, said fuel tank having an annular configuration, and a carburetor located in the central space of the fuel tank for supplying fuel from the tank to the crankcase. 